Geophysical surveying, such as with seismic or electromagnetic sensing, are techniques where two- or three-dimensional “pictures” of the state of an underground formation are taken. Geophysical surveying takes place not only on land, but also in marine environments. Marine-based geophysical surveying faces significant challenges that are not faced by land-based surveying systems. For example, performing geophysical surveys under surface obstructions (e.g., sea ice) or around fixed objects or formations (e.g., rigs, derricks, coral, volcanoes), particularly where the obstruction completely covers the surface, is difficult.